Searching reveals that several questions have been asked about William Adams on this sub over the years, but none of them have answers. This had lead me to wonder how much we can really say we authoritatively know about the life and times of the man in the environment he found himself in when he shipwrecked on Japan.
From what I understand, much of what we know about William Addams stems from the letters he sent his wife and letters from other Europeans who interacted with him. They seem to be the source of some of the weightier facts about him, such as his status as an advisor and influence to Tokugawa Ieyasu. Do any Japanese primary sources corroborate the information gleaned from Adam's personal letters?
Even without this, it seems likely enough that Adams certainly became a samurai and figure of some reknown given that he is both revered and respected in Japan given that towns, festivals, and other monuments bear his name. Still, I'm curious about some of the finer details:
*Would Adams have received martial training as a samurai (Katana, spear, horseback riding) or was his status strictly social and ceremonial in nature? *Is there any indication Adams fought in the service of Ieyasu at any time? *Did Adams ever desire to return to England, or was he content to remain in Japan for the duration of his life?
Thanks for any contributions, and for all that you do here!
FYI, by the time Adams arrived in Japan in 1600, the Sengoku was almost over (or over, if you count Sengoku to the construction of Azuchi or the unification of the country by Hideyoshi in 1590).
So the answer to the title question is: none, or next to none.
Adams main influence was working as an intermediary and diplomat between the Edo Bakufu and Europe, though they did have him help construct western-style ships, and according to Sagami Province local history he was hired for his knowledge in gunpowder weapons. The most "active" military thing Adams might have done in Japan would be to help get the Edo Bakufu in contact with English and Dutch merchants for the purchase of cannons for besieging Osaka in 1614, but I don't believe there's record for that.
Adams received permission to return to England in 1613 with John Saris. Adams and Saris didn't really get along, which might have played in part to Adams decision to stay in Japan. But even then, it would mean he didn't want to go back to England badly enough to just go with Saris. Perhaps playing into this was also that Adams already had a Japanese wife and a son.
Slightly later Edo-era local histories from Nagasaki and Sagami confirm that Adams was a samurai. The local history of Sagami lists his tiny fief in Hemi in modern Yokosuka, Kanagawa Prefecture, though misidentify him as Korean or Chinese (or maybe those words were used as shorthand for "foreign"). Nagasaki local history correctly identify him as English.